Portable food mixer



A ril 6, 1965 A. l. APPLETON 3,176,968

PORTABLE FOOD MIXER Original Filed June 28, 1956 5 Sheets-Sheet 1Inventor ARTHUR I, APPLETON April 6, 1965 A. 1. APPLETON 3,176,968

PORTABLE FOOD MIXER Original Filed June 28, 1956 5 Sheets-Sheet 2Inventor ARTHUR I. APPLEToN April 6, 1965 A. 1. APPLETON 3, 7 68PORTABLE FOOD MIXER Original Filed June 28, 1956 5 Sheets-Sheet 3Inventor ARTHUR I. APPLETON PM MW W/ j A/%/ Mm @a,

April 6; 1965 A. l. APPLETON PORTABLE FOOD MIXER 5 Sheets-Sheet 4Original Filed June 28, 1956 Invento r ARTHUR I. APPLETON April 6, 1965A. l. APPLEZTON 3,176,968

PORTABLE FOOD MIXER Original Filed June 28, 1956 5 Sheets-Sheet 5 v 4! 1w P/ I44 I36 45 .f

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Inventor ARTHUR I, APPLETON United States Patent s,17s,9ss PORTABLE FOODMIXER Arthur I. Appleton, 1713 Wellington, Northbrook 13, Ill. Originalapplication June 28, 1956, Ser. No. 594,574, new Patent No. 2,%5,452,dated Sept. 22, 1959. Divided and this application Apr. 29, 1959, Ser.No. 809,687 6 Claims. (Cl. 259-108) This application is a division of mycopending application Serial No. 594,574, filed June 28, 1956, nowPatent No. 2,905,452, which is a continuation-in-part of my priorapplication Serial No. 256,066, filed November 13, 1951, covering aMixer, now abandoned.

The present invention pertains generally to mixing apparatus and, morespecifically, to a novel, power-operated device for mixing variousfluid, solid and pulverous materials. It finds particular, but by nomeans exclusive, utility when embodied in a household appliance formixing foods. The invention is, however, adapted to serve with equalfacility in commercial or industrial applications for mixing othersubstances as well as foods.

One object is to provide a mixer of the type set forth and which willinclude a controllable heating means, adapting the device for use indelicate cooking operations, such as the making of certain frostings,and also permitting the device to be used for direct cooking of one ormore of the ingredients to be mixed or beaten.

Still another object is to provide an appliance of the foregoing typehaving a particularly attractive appearance and which, when idle, willbe completely closed so as to eliminate the necessity for a plastic dustcover.

Other objects and advantages will become apparent as the followingdescription proceeds, taken in connection with the accompanyingdrawings, in which: 7

FIGURE 1 is a perspective view of an illustrative mixer embodying thepresent invention;

FIG. 2 is an enlarged, vertical sectional view taken through thelongitudinal medial plane 2-2 of the mixer shown in FIG. 1;

FIG. 3 is an enlarged, vertical sectional view taken through the planeof lines 3-3 of FIG. 1;

FIG. 4 is a fragmentary plan view of the mixer as shown in FIGURE 1,certain portions of the casing being broken away to illustrate internaldetails;

FIG. 5 is an enlarged, horizontal sectional view taken through the planeof lines 5-5 of FIG. 2;

FIG. 6 is an enlarged, vertical sectional view taken through the planeof lines 6-6 of FIG. 2;

FIG. 7 is an enlarged, fragmentary, horizontal sectional view throughthe plane of lines 7-7 of FIG. 2, and illus trating the planetary geardrive;

FIG. 8 is an enlarged, exploded perspective view of the power head andbeater coupling arrangement embodied in the mixer of FIG. 2; and

FIGS. 9-12 are sectional views taken through the planes of lines 9-9,10-10, 11-11, and 12-12, respectively, of FIG. 8.

While the invention is susceptible of various modifications andalternative constructions, an illustrative embodiment has been shown inthe drawings and will be described below in considerable detail. Itshould be understood, however, that there is no intention to limit theinvention to the specific form disclosed, but on the contrary, theintention is to cover all modifications, alternative constructions andequivalents falling within the spirit and scope of the invention asexpressed in the appended claims.

General organization Referring more specifically to the drawings, theinvention is there exemplified in a novel mixing device which, in thisinstance, is a household food mixer 30. In general, the mixer comprisesa base 31 having an upstanding power head 32, a. mixing bowl 34 whichtelescopes over the power head, and a pair of counter-rotating impellers35, 3d drivingly supported from the power head 32. For purposes ofdescription, the impeller 35 will be referred to herein as the upperimpeller while the impeller 36 will be called the lower impeller (seeFIG. 3). The bowl 34- is equipped with a cover 38, which may be oftransparent material, having a center handle 39.

The base 31 of the illustrative mixer 30 is assembled upon a bed 40(FIG. 2) having feet of rubber or similar material to prevent sliding ofthe mixer on the counter, table top, or other horizontal surface whichsupports it. The bed so is surmounted by a hood or casing with slopingside walls extending upwardly from a peripheral flange .1 and curvinggracefully into a top wall. The casing may, for example, be of stampedsheet metal, cast light metal, or molded plastic material, securelyfastened to the bed 4%. The side walls of the casing may also haveexternal embossments or ribs to serve as stilieners and enhance itsappearance.

The mixing bowl 34 in its preferred form, has a substantially annularshape and may be constructed from a wide variety of materials includingaluminum, stainless steel and glass. In the present instance, the bowl34 comprises a dished or concave bottom :2 merging into an outer sidewall which has a slight outward and up ward taper, terminating in aperipheral rim adapted to register with the rim of the cover 38. Thebowl bottom 42 also merges with a hollow central boss 44, flared out atits base and tapered toward its upper or free end which is situated ator near the top of the bowl 34. The internal contour of the boss 44 iscomplementary with the exterior contour of the power head 32. Theseparts are so proportioned that the bowl boss can be centered on, andtelescoped over, the power head 32 with the bottom of the bowl restingupon the top of the base casing 31.

Turning next to the counter-rotating impellers-35, 36, it will beperceived that the same have been constructed and arranged to sweep theentire normally usable volume of the mixing bowl 34-. By normally usablevolume is meant the maximum volume at which a user would ordinarily fillthe bowl whil still permitting the same to be handled conveniently andwithout likelihood of spillage. By the same token, the impellers 35, 36have been constructed and arranged to sweep exceptionally close tosubstantially the entire inside wall surface of the bowl 34 includedwithin the normally usable volume of the same. This avoids the buildingup of accumulations of unmixed or poorly mixed substances on the bowlwalls and insures a miiximum yield-of properly mixed materials from thebow In the present instance, the top impeller 35 is driven in aclockwise direction (as viewed from the top in FiG. 4) while the bottomimpeller 36 is driven in a counterclockwise direction (also as viewedfrom the top). Since each impeller is formed with a pair ofdiametrically opposed positions, this means that each impeller sweepspast the other twice per relative revolution. While it is possible tooperate the impellers 35, 36 at various individual rotational speeds, ithas been found desirable to proportion each impeller and to select itsdriving speed so that the opposed bowl reactions or bowl drags due tothe counter-rotation of the impellers will balance out approximately,thus avoiding a tendency toward rotation of the bowl 34 about the powerhead 32. This balanced condition can readily be determined in thelaboratory by loading the bowl with extremely heavy or viscous materialsand by varying the individual speeds of the impellers until the bowl nolonger tends to turn. An unbalanced bowl reaction may, of course, bedealt with by the straight forward expedient of utilizing a keyed orsplined connection between the hollow bowl boss 44 and the power head32.

The power head 32 includes concentrically mounted and counter-rotatingimpeller drive shafts 45, 46 powered by a motor 47 mounted within theinterior of the mixer base 31 and coupled to the concentric shafts bymeans of a transmission disposed within a gear housing 48.

To complete the description of the general organization and arrangement,beneath the annular mixing bowl 34 for heating the contents, and on thetop of the mixer base 31 is an annular heating element 4% supported by asaucerlike pan or baffle plate 54) mounted upon a plurality ofinsulating buttons spacing the bafile plate 50 from the mixerrbase. Theheating element is connected by means of a power cord to a source ofelectric current, and may be regulated by means of a switch 51controlling a rheostat or the like, as shown in FIGURE 1 carried on thetop of the mixer base.

Impeller construction Turning first to the construction of the impellersshown in FIGS. 2 through 12, two individual impellers 35, as areemployed.

These individual impellers together make up an assembly including thetop impeller 35, which comprises a central hub 52 (FIGS. 2, 4 and 8)with a substantially flat contour and merging into opposed outwardlyextending arms 53. The central hub of the impeller has (FIGS. 8-l2) agenerally circular opening 54 adapted to fit about the upper end of theimpeller drive shaft. The side wall of the opening 54 is formed withequally spaced, in the present instance six, substantially verticalslots or grooves 56 for coupling with a plurality, shown as three,inclined or helical driving lands 57 carried on the outer peripheralsurface of a bushing 58 non-rotatably fixed to the inner beater driveshaft 45 of the power head 32. In the illustrative form of drive shown,these inclined or helical driving lands 57 are angled to slope upwardlyin the direction of beater rotation. They, in combination with the slots56 in the opening through the impeller hub, constitute not only atoothed drive to turn the impeller, but additionally obtain the resultof positively locking the impeller to the drive shaft while the shaft isrotating. When the drive shaft is stopped, the impellermay easily beremoved by lifting the impeller directly, giving it a slight twist inthe direction of rotation to separate the elements, or by lifting thebowl, as an incident to which the impellers are lifted oif the driveshafts.

The lower or bottom impeller 36 is coupled to be driven to the outerimpeller drive shaft 46 of the power head 32 in a like fashion. In thiscase, a sleeve or bushing 59 is mounted on the upper end of this innerdrive shaft, presenting helical or inclined lands 60 on the peripheralsurface, seated within slots 61 formed in the side wall of asubstantially central opening 62 machined in the hub 63 of this bottomimpeller. Again, the lands at) slope upwardly in the direction of beaterrotation, being of the opposite hand to the lands 57 driving the topbeater since the Ibeaters or impellers counter-rotate.

For convenience in fastening the bushings 58, 59 on V the impeller driveshafts 45, 4-6 respectively, the upper ends of these shafts are formedsquare and are received 7 within substantially square openings 64, as inthe upper and lower bushings 58, 59 respectively, although it will beunderstood that this particular arrangement may be modified if founddesirable. To hold the said upper and lower bushings in place, a capscrew 66 may be employed, threaded into the inner shaft and thus holdingthe bushings in permanent assembled relation.

It will also be observed that the upper sleeve or bushing 58 when inplace on the inner drive shaft 45 serves as a pilot to guide the inneror lower impeller 36 toward toothed engagement with the driving elementtherefor presented by the lower bushing 55% on the outer impeller driveshaft 46. .This pilot effect facilitates placing the savages l lowerimpeller properly located and in driving relation on the outer driveshaft.

Affixed to, and preferably integral with the opposed outwardly extendingarms of the top impeller 35, are drooping blade portions 67, as bent todepend in substantially straight relation with the outer side wall ofthe mixing bowl, the leading edge es of the depending portion beingsubstantially straight and located spaced but a short distancethroughout its length from the inside of the bowl side wall, while thetrailing edge '76 is spaced at largerdistance to pitch the blade fordeflecting material inwardly.

The lower ends of the depending blades 67, 68 of this upper or topimpeller 35, curve inwardly slightly generally following the curvatureof the dished bowl bottom.

The lower or bottom impeller 36 nests with the upper impeller and issupported for driving relation by the outer drive shaft 46 of the powerhead 32 centrally disposed within the mixing bowl. This bottom impeller,has a central hub 63 of substantially cylindrical shape within which theslotted opening 62 constituting one element of the toothed drive isfashioned. Extending downwardly from the under face of this central hub'63, and fixed integrally throughout are a pair of diametrically opposedarms 71 each defining an inner blade 72 (FIG. 2) which merges into abottom blade 73. As shown in FIGS. 2 and 4, the inner and bottom bladesare slightly curved to conform to the tapered central boss of the mixingbowl in the case of the inner blades, for increased mixing efiiciency,in the case of the bottom blades for the latter reason alone. Thus theinner blades are adapted to nest closely along the central boss of thebowl.

This lower impeller 36 also has, in the illustrative form shown in FIG.2, a section adapted to sweep through the intermediate portion of thecontents within the bowl. Accordingly, each of the opposed inner blades'72 of the lower impeller carries a pair of outwardly extending anddownwardly curving impeller elements 74, spaced uniformly apart andjoining the bottom blades 73 adjacent the ends. These impeller elementsmay be constructed of fiat rigid strips of the same material from whichthe blades themselves are fashioned, brazed or otherwise socured inplace on the inner impeller, to occupy an intermediate position in thebowl cross section. In one sense, the impeller elements 74-, '75 may besaid to pass between the inner blades of the lower impeller 36 and thedownwardly depending and outer blades or blade sections 6'7, 63- of thetop impeller 35. Thus upon counter-rotation of the upper and lowerimpellers, it will be perceived that the upper impeller tends to deflectmaterial inwardly as the result of the slight pitch of thedependingblade sections, While the lower impeller tends to deflectmaterial outwardly from the tapered central boss of the mixing bowl, andas well upwardly from the bottom of the bowl, this same lower impelleralso carrying the impeller elements for sweeping through, agitating andmixing the contents in the intermediate sections of the bowl. Thecounter-rotating impellers pass with respect to the other setting up aplurality of currents in the mix, including some toward the center ofthe bowl, someaway from the center of the bowl, some toward the bottomof the bowl and some away from the bottom of the bowl.

Power head and transmission For driving as well as supporting theimpellers 35, 36 (FIGS. l-lZ), the present invention contemplates theuse of an upstanding column 32 within which are journalled the pair ofcounter-rotating concentric impeller drive shafts 45, as. The shaft 45,which is the inside Shaft, is

' within a centering cone hti which may be built up out of plastic,metal, or hard rubber material, and has a tapered stepped section astoward the lower end, externally threaded for securing within the upperend of a gear housing 48 or the like enclosing the impeller drive shaftstransmission or gear drive assembly.

The taper of the centering cone 96 is preferably complemental to that ofthe inside of the mixing bowl boss, so that the cone is adapted to serveas a centering means for the bowl. The upper ends of the drive shafts4-5, 46 are each provided, as has hereinbefore been described in detail,such that the impellers may be instantaneously detached from these driveshafts, either individually or as an incident to lifting the bowl offthe mixer base. The arrangement also serves to enable the impellers tobe connected to their drive shafts with utmost ease and speed.

In the present instance, the outer drive shaft 46 is turned directly bythe motor 47, and by means of a planetary drive means contained withinthe housing 43, counter-rotation is imparted therefrom to the insideshaft 45. The outside shaft 46, thus is journalled within the centeringcone 96, and is connected by means such as threads or the like, at itslower end, with a sleeve 99 machined to receive a worm wheel Hill. Thissleeve 99 at its very lower end is milled with outwardly extending gearteeth forming a sun gear 1171. The outer concentric shaft 46, sleeve,worm wheel and sun gear assembly, nest within a planetary gear array102, the downward thrust on the shaft 46 being taken up as by means of alower gear disc 103 supported within an internal ring gear housing 104pinned (as by a pin M5) to the inner impeller drive shaft 45. Theinternal ring gear housing 164 is constructed to present a lower steppedsection, seating within a recess 166 formed in the housing cover closingthe transmission or drive gear housing 48. The shoulders 1428 presentedby the lower stepped bearing surrounding the inner drive shaft 45, serveto take up downward thrust on this shaft, bearing against a horizontalannular bearing seat 109 provided laterally of the recess 106 within thehousing cover.

The sun gear 101 drives, as shown in FIG. 7, the assembly of planetgears 192, which through the internal ring gear housing 104 impartsrotation in a counter-direction to that of the sun gear, to the innerimpeller drive shaft 45. Speed reduction of this inner shaft is alsoeffected by the transmission shown in the drawings, the particular speedratio being somewhat a matter of choice as hereinbefore described.

It has been found relatively simple with this transmission to obtainimproved mixing action with the counter-rotating beaters by selecting aspeed ratio at which the points where the oppositely moving beaterspass, constantly rotate but slowly about the power head. If the speedratio between the outer and inner impeller drive shafts is a wholenumber, the points at which the blades pass will remain stationarywithin the mixing bowl. If on the other hand, the speed ratio is somefractional number, these points will move constantly about the powerhead in one direction or the other, depending upon the particular speedratio. It has been found that a slow rate of travel of these pointsuniformly in one direction produces an improved mixing action.

Counter-rotation of the shafts 46 is effected by means of the wormwheel, sun gear and planetary gear drive contained within thetransmission housing 48. In the present instance the worm wheel ltltl isdriven by means of a worm gear 11% carried by a motor shaft 111 poweredby the motor 47 supported within the interior of the base 31 of themixer.

Referring to FIGS. 5 and 6 more particularly, in the present instancethe motor 47 is fastened, as by bolts 112, to a mounting bracket whichis aflixed to the bed 40. The worm and worm gear comprise a primaryspeed reduction means and may be encased Within the transmission housing43 and the motor housing 113, which latter housing may be cast orotherwise formed as a part separate from the transmission housing 48, ormade integrally therewith. In either event, the transmission housing 43is fastened as by means of bolts through feet 116, to the bed 40, toprovide a firm and stable structure for mounting the power head and themotor within the base 31 of the mixer. Within the motor housing 113, themotor 47 is mounted for rotation, commonly an electric drive motor ofthe Universal type, and is equipped with a cooling fan 118 at the motorshaft end remote from the worm gear 110. The motor housing has openingssuch as 11.9 for the passage of air through and by the motor windings.The motor fan 118, thus causes a constant movement of air through theinterior of the mixer base 31, this constant movement or circulation ofair having [or a first purpose, the cooling of the motor 47.

For driving the impellers 35, 36 at selectively variable speedscorresponding to the requirements for the substances being mixed in thebowl 34, the motor 47 may be equipped with an adjustable governor 125.While the present invention is not particularly concerned with thedetails of the governor, it might be noted that, in this instance, thegovernor is constructed as a component part of the motor assembly and isprovided with an upstanding adjusting stem 126 terminating at its upperend in a speed control dial, which is actually a calibrated manualadjusting dial 128. To preclude spilled material from entering thecasing via the opening through which the adjusting stem 126 extends, thetop wall of the casing has an embossment or raised island 129 formedtherein and disposed in underlying relation with the speed control dial128. Power for the motor 102 may be supplied as by means of a powersupply cord 130 which enter-s the back wall of the casing or base 31 ofthe mixer.

Mixer bowl heating In order to broaden the utility of the mixer 30,provision is made to adapt the same for use in even the most delicatecooking operations and also for direct cooking or Warming of one or moreof the ingredients to be mixed or beaten. This is accomplished byequipping the mixer with a controllable heating means, such as a tubularor annular heating element 49 of the type sometimes referred to as aCalrod unit.

Accordingly, the top wall of the mixer base is cut away to form agenerally circular opening 131. Within this opening and mounted by meansof a mounting plate 132, asaucer-like pan or bafiie plate 50 is carriedspaced from the mixer base to provide a troughed annular sec tionconstituting a support means for the annular heating element 49. In thepresent instance, for the purpose of lending rigidity to the structure,the baffle plate in the central portion thereof is formed with a turnedup central rim 133 which is press-fit onto an indexing collar 135. Thecollar 135 in turn fits comparatively snugly within a groove formedabout the outside of the centering cone $6.

The mounting plate 132, as mentioned before, constituting the mount forthe bafide plate 50, is carried on the upper flat surfaces presented byoppositely disposed vertical ribs 136, formed as shown, integral withthe transmission housing (43) casting. These ribs 136 laterallyprojecting and rigid (FIG. 4) form a stable and firm support for themounting plate 132 and likewise the bathe plate 59.

The 'bafile plate 50 is provided toward its outer edge with a sectionbent to slope gently upwardly and presenting a substantially flatannular part 140 and at its very outer periphery with a reverse curvedsection or downwardly turned rim 141. The relative size of the opening131 in the base of the mixer and the bafile plate 59, is such as toprovide for substantial clearance between the opening and the plate.Thus the baffle plate is supported level by means of the mounting plate132, on a plurality of insulating buttons 142, these insulating buttonsalso serving to mount the annular heating element 4) itself. In thepresent instance, each of these arrases buttons M2 is made of bondedmica, and is generally cylindrical in shape with a raised shoulder 143substantially centrally thereof, the opposed cylindrical end portions ofeach of the buttons being receive-d in like sized alined openings cut inthe bafiie plate 56 and mounting plate 132. The shoulder 143 serves as aspacer separating the mounting and battle plates. For securing theheating element 49 within the troughed annular section of the battleplate 5%, the heating element shell on the under side has secured to ita plurality of downwardly extending split pins 144 sized to snuglywithin a central cylindrical bore in the mica insulating buttons 142.For facilitating entry of the pins in the bores, the upper and lowerends of the bores (the button is reversible) are chamfered. In thiscase, frictional engagement of the pins 144 within the openings in theinsulating buttons 142, holds the pins against endwise movement, andthus the heating unit 49 in place. Nevertheless it is relatively simpleto remove the heating unit, which may be done by forcing the pins fromthe insulating buttons.

The heating unit, as described hereinbefore, is of conventionalconstruction, including a circular array of solidconductor heating wires145, surrounded by insulating material 159 within a steel, or other likematerial, shell. For convenience, the heating unit may be connectedthrough the same power cord 130 providing current for the mixer drivemotor '47, but for regulating the heat output it is preferable toconnect the unit to the source of current through a variable rheostat orthe like, controlled by an adjusting dial 51, for regulating the currentsupplied to the heating unit and thus the heat developed.

The saucer-like pan or baffle plate 50 not only supports the heatingunit 49, but also forms a base with the said heating element forsupporting the mixing bowl 34. In addition, the baffie plate 50functions to reflect heat upwardly toward the mixing bowl, focusing ofthe heat being aided by the flat upwardly sloping section 14% and rim141011 the outer edge of the bafile plate.

This same downwardly turned rim also functions to deflect downwardly andaway from the bowl, air moving by convection through the gap between theunder side or" the baffleplate and the edge of the opening 131 withinthe base of the mixer. As has been described hereinbefore, air isconstantly being circulated within the interior of the base of the mixerby the motor fan, this movement of air and circulation of warm currentsof air through the housing creating temperature differential betweenvarious points in the housing and resulting in the development ofconvection air currents. One such series of curing contents within themixing bowl. Since heat is transmitted to the baffle plate 50, which istransmitted directly to the air immediately adjacent the under surfaceof this plate, the layer of air under the baffle plate being warmer thanthe surrounding air tends to how outwardly toward the gap between thebathe plate and the opening in the mixer base. This movement of air maybe observed as constant, flowing upwardly through the space or gap andbeing directed downwardly and away from the mixing bowl by theconcavecurved under surface of the baflle plate rim itself.

This constant circulation of air through the gap between the bafiieplate '50 and mixer base opening 131, also serves to insulate the mixerbase housing or casing walls from heat generated by the heating unit. Inother words, the material of the base of the mixer being plastic, metalor the like, if subjected to excessive heat from the heating unit maywarp or be stressed, becoming too hot to touch, or in the case ofplastic, bending and deforming in an undesirable manner. The constantcirculation of air and the movement of air through the gap between thebaffle plate 50 and the mixer base by convection air currents, reducesthe heat transferred to the mixer base substantially. Furthermore, theheating element is located about the central power head and passes overthe motor 47 supported within the base of the mixer. Heat generated inthe heating element and transferred by conduction, radiation orconvection downwardly affects the temperature of air surrounding themotor. By use of the convection currents causing the constant flow ofair beneath the pan or plate 5%, the motor is insulated from the heatingunit.

'The heating unit 4% is thus enabled to operate for extended periods forthe generation of heat and heating contents within the mixer bowl,without deleteriously affecting the operation of the drive motor for thepower head of the mixer, or raising dangerously the temperature of thewalls of the mixer base.

Further facilitating the circulation of air within the mixer base 31,and furnishing a source of cooling air, is accomplished by a relativelynarrow air gap or spacing 352 between the peripheral edge of the bed 44of the mixer base, and the adjacent lower edge of the walls of the base.This narrow air gap extends completely around the mixer base,interrupted at only a few points (shown as four) by rubber feet 159which serve both to mount the bed and also to mount the housing of themixer base. As shown in FIGS. 2 and 5, the inner side and end walls or"the mixer base housing are fashioned with curved ribs 3 is, under whichthe rubber feet 159 are fastened as by threaded bolts 161 or the like.The bed 4t is notched, as at 162, to embrace the rubber feet 159 in theregion of a peripheral groove, thus effectively locking the bed and feettogether. These plurality of feet support the bed 40, and since they aremounted directly under the ribs formed on the inside of the walls of themixer base casing, also support this casing.

I claim as my invention:

1. In a portable mixing device for foods and other substances having abase including a housing, an upstanding power head on said base andextending above said housing including stationary outer members androtating inher members, the combination comprising, an annular mixingbowl having a central portion adapted to removably fit over said powerhead and be held by said stationary members of said power head insubstantially concentric relation therewith, said mixing bowl alsohaving a' bottom, power driven impeller means removably connected tosaid rotating members of said power head and disposed within said bowlso as to rotate adjacent the bottom thereof and stir contents therein,and means carried by said power head providing a temperature controlableheat emitting support for the bowl including an annular electricalheating element carried in surrounding relation with said power headunder said bowl, said heating element being in substantially coextensiveengagement with the bottom of the bowl to support and heat said bowl andits contents, and a member fixed to said power head stationary membersand extending laterally thereof beneath said annular heating element forsupporting said annular heating element and a bowl received thereon.

2. In a portable mixing device for foods and other sub- 7 stances havinga base including a housing, an upstanding power head on said base andextending above said housmg including stationary outer members androtating in her members, the combination comprising, an annular mixingbowl having a central portion adapted to removably fit over said powerhead and be held by said stationarymemb'ers of said power head insubstantially concentric relation therewith, said mixing bowl alsohaving a bottom, power driven impeller means removably connected to saidrotating members of said power head and disposed within said bowl so asto rotate adjacent the bottom thereof and stir contents therein, andmeans carried by said power head providing a temperature controllableheat emitting support for the bowl including an annular electricalheating element carried in surrounding relation with said power headunder said bowl, said heating element being in substantially coextensiveengagement with the bottom of the bowl to support and heat said bowl andits contents, a member fixed to said power head stationary members andextending laterally thereof beneath said annular heating element, and anannular baftle plate carried by said support member and supporting saidheating element and a bowl received thereon, said housing having asubstantially circular opening therein concentrically arranged withrespect to said baffle plate and having a diameter greater than saidheating element, said bafiie plate being spaced at its outer peripheryfrom the edge of said housing opening to provide an insulating 3. In aportable mixing device for foods and other substances having a baseincluding a housing, an upstanding power head on said base and extendingabove said housing including stationary outer members and rotating innermembers, the combination comprising, a power unit in said housing onsaid base and connected to said rotating members, an annular mixing bowlhaving a central portion adapted to removably fit over said power headand be held by said stationary members of said power head insubstantially concentric relation therewith, said mixing bowl alsohaving a bottom, power driven impeller means removably connected to saidrotating members of said power head and disposed within said bowl so asto rotate adjacent the bottom thereof and stir contents therein, meanscarried by said power head providing a tem erature controllable heatemitting supportfor the bowl including an annular electrical heatingelement carried in surrounding relation with said power head under saidbowl, said heating element being in substantially coextensive engagementwith the bottom of the bowl to support and heat said bowl and itscontents, a member fixed to said power head stationary members andextending laterally thereof beneath said annular heating element, anannular bafiie plate carried by said support member and supporting saidheating element and a bowl received thereon, said housing having asubstantially circular opening therein concentrically arranged withrespect to said baffie plate and having a diameter greater than saidheating element, said bafile plate being spaced at its outer peripheryfrom the edge of said housing opening to provide an insulating gap, anda fan in said housing operated by said power unit for moving airoutwardly of said bafiie plate on the underside thereof to saidinsulating gap.

4. In a portable mixing device for foods and other substances having abase including a housing, an upstanding power head on said base andextending above said housing including stationary outer members androtating inner members, the combination comprising, an annular mixingbowl having a central portion adapted to removably fit over said powerhead and be held by said stationary members of said power head insubstantially concentric relation therewith, said mixing bowl alsohaving a bottom, power driven impeller means removably connected to saidrotating members of said power head and disposed within said bowl so asto rotate adjacent the bottom thereof and stir contents therein, meanscarried by said power head providing a temperature controllable heatemitting support for the bowl including an annular electrical heatingelement carried in surrounding relation with said power head under saidbowl, said heating element being in substantially coextensive engagementwith the bottom of the bowl to support and heat said bowl and itscontents, a member fixed to said power head stationary members andextending laterally thereof beneath said annular heating element forsupporting said annular heating element and a bowl received thereon, andmeans for controlling the amount of heat emitted by said heatingelement.

5. In a portable mixing device for foods and other substances having abase including a housing, an upstanding power head on said base andextending above said housing including stationary outer members androtating inner members, the combination comprising, an annular mixingbowl having a central portion adapted to removably fit over said powerhead and be held by said stationary members of said power head insubstantially concentric relation therewith, said mixing bowl alsohaving a bottom, power driven impeller means removably connected to saidrotating members of said power head and disposed within said bowl so asto rotate adjacent the bottom thereof and stir contents therein, andmeans carried by said power head providing a temperature controllableheat emitting support for the bowl including an annular electricalheating element carried in surrounding relation with said power headunder said bowl, said heatelement being in substantially coextensiveengagement with the bottom of the bowl to support and heat said bowl andits contents, a support member fixed to said power head and extendinglaterally thereof beneath scid heating element, an annular bafiie platebetween said support member and said heating element, and a plurality ofcircumferentially spaced insulating buttons projecting upwardly fromsaid support member and carrying both said baffle plate and said heatingelement, said buttons being arranged to project above said bafiie plateand each having a vertical bore, said annular heating element resting'onsaid insulating buttons and having a plurality of circumferentiallyspaced mounting pins on the underside of said element adapted to bereceived in said bores therein.

6. In a portable mixing device for foods and other substances having abase including a housing, an upstanding power head on said base andextending above said housing through a substantially circular openingtherein including stationary outer members and rotating inner members,the combination comprising, an annular mixing bowl having a centralportion adapted to removably fit over said power head and be held bysaid stationary members of said power head in substantially concentricrelation therewith, said mixing bowl also having a bottom, power drivenimpeller means removably connected to said rotating members of saidpower head and disposed within said bowl so as to rotate adjacent thebottom thereof and stir contents therein, and means carried by saidpower head within said housing opening providing a temperaturecontrollable heat emitting support for the bowl including an annularelectrical heating element carried in surrounding relation with saidpower head under said bowl, said heating element being in substantiallycoextensive engagement with the bottom of the bowl to support and heatsaid bowl and its contents, a support member fixed to said power headand extending laterally thereof, a plurality of buttons of insulatingmaterial projecting upwardly from said support member and supportingsaid annular heating element, and an annular troughed baffle platebetween said heating element and said support member spaced at itsperiphery from the edge of said housing opening and reflecting heatupwardly away from the latter and said support member toward a mixingbowl resting on said heating element.

References Cited in the file of this patent UNITED STATES PATENTS2,097,825 Wolcott Nov. 2, 1937 2,513,254 Savage et a1 June 27, 19502,605,382 Kircher et a1. July 29, 1952 2,625,642 Davis Jan. 13, 19532,638,329 Weygand et al May 12, 1953 2,657,299 McNairy Oct. 27, 1953

1. IN A PORTABLE MIXING DEVICE FOR FOODS AND OTHER SUBSTANCES HAVING ABASE INCLUDING A HOUSING, AN UPSTANDING POWER HEAD ON SAID BASE ANDEXTENDING ABOVE SAID HOUSING INCLUDING STATIONARY OUTER MEMBERS ANDROTATING INNER MEMBERS, THE COMBINATION COMPRISING, AN ANNULAR MIXINGBOWL HAVING A CENTRAL PORTION ADAPTED TO REMOVABLY FIT OVER SAID POWERHEAD AND BE HELD BY SAID STATIONARY MEMBERS OF SAID POWER HEAD INSUBSTANTIALLY CONCENTRIC RELATION THEREWITH, SAID MIXING BOWL ALSOHAVING A BOTTOM, POWER DRIVEN IMPELLER MEANS MOVABLY CONNECTED TO SAIDROTATING MEMBERS OF SAID POWER HEAD AND DISPOSED WITHIN SAID BOWL SO ASTO ROTATE ADJACENT THE